9-128 Section 916. Erosion and Sedimentation Control Materials
916.01 Stone Used For Erosion and Sedimentation Control
Provide cobblestone, coarse aggregate 3×1, and riprap for erosion and sedimentation control on slopes, in ditches, and to construct erosion control devices, including check dams . Furnish natural stone that is sound, non-stratified, durable rock . Unless otherwise specified and not prohibited by permit, the Contractor may use sound pieces of broken concrete free of protruding reinforcement . Do not use crushed HMA pavement or broken brick as erosion and sedimentation control material.
A.Cobblestone . Furnish c obblestone that consist s of rounded or semi -rounded rock fragments with an average dimension from 3 to 10 inches.
B.Coarse Aggregate 3x1. Furnish c oarse aggregate 3×1 that meet s the requirements of commercially graded material with particle sizes from ¾ to 3 inches.
C.Riprap . Furnish r iprap that is natural stone, solid precast concrete blocks of Grade 3000 concrete, or sound pieces of broken concrete . Riprap must not contain soil . Randomly score the face of the precast concrete blocks to provide plane-of -weakness joints in sections with areas from 4 to 9 square feet . Lifting lugs, cast into concrete blocks, must not project above the finished concrete surface. The Department classifies riprap as plain or heavy, based on the horizontal cross section dimensions ( “footprint ” dimensions ) and the in-place thickness of the individual pieces.
1.Plain Riprap. Provide n atural stone and broken concrete with footpr int dimensions from 8 to 16 inches and an in- place thickness of at least 16 inches . The Contractor may use smaller pieces to fill spaces for better slope protection. Provide p recast concrete block at least 6 inches thick with a surface area no greater than 15 square feet.
2.Heavy Riprap . The smallest footprint dimension for natural stone and broken concrete must be at least 16 inches. The maximum-to -minimum dimension ratio must be no greater than 3:1. The in-place thickness must be at least 36 inches. Provide p recast concrete block at least 16 inches thick with a surface area no greater than 20 square feet. MDOT Standard Specifications for Construction Section 916 9-129 D. Requirements for Specific Erosion and Sedimentation Control Applications
1.Checkdams. Construct c heckdams for ditch es with grades less than 2% using cobblestone or broken concrete from 2 to 4 inches . Construct checkdams for ditches with grades 2% or greater using cobblestone or broken concrete from 3 to 10 inches.
2.Stone Filled Bags . Furnish coarse aggregate 6A , or open- graded aggregate 46G.
3.Sand Fi lled Bags. Furnish Class II granular material.
4.Aggregate Cover . Furnish dense-graded aggregate 21AA, open-graded aggregate 46G, coarse aggregate 6A, or coarse aggregate 3×1 produced natural aggregate, iron blast -furnace slag, reverberatory furnace slag, or crushed Portland cement concrete.
5.Gravel Access Approach . Furnish coarse aggregate 3×1, or as approved by the Engineer , that is produced from natural aggregate, iron-blast furnace slag, reverberatory furnace slag, or crushed Portland cement concrete.
916.02 Silt Fence
Geotextile for an erosion-control silt fence must meet the requirements of subsection 910.04. Attach geotextile to machine- pointed, No. 2 common grade hardwood posts with at least five staples through wood lath at least ⅜ inch thick and 2.0 feet long. Maximum post spacing is 6½ feet. Furnish p osts at least 36 inches long with a cross sectional area of at least 2¼ square inches and a smallest dimension of 1½ inches. Identify the fabricator with at least two permanent markings or affixed labels on each assembled roll of silt fence.
916.03 Temporary Plastic Sheet or Geotextile Cover
Mend or patch torn or punctured plastic sheets or geotextile cover with additional material of the same quality.
A.Sheeting Material . Furni sh plastic sheet ing material at least 6.0 mils thick with a UV ray inhibitor or PVC at least 10 mils thick. Use PVC material instead of plastic sheet from November 15 to April 1 or if expecting freezing conditions . Store and handle plastic sheet and PVC material in accordance with the manufacturer ’s recommendations . Do not expose sheeting material to heat or direct sunlight that would diminish strength or toughness. MDOT Standard Specifications for Construction Section 916 9-130 B. Geotextile Cover . Geotextile cover must meet the requirements of subsection 910.03.A for geotextile blanket.
916.04 Inlet Protection Fabric Drop
Furnish geotextile silt fence fabric meeting the requirements of subsection
916.02 or geotextile blanket meeting the requirements of subsection
910.03 A . Furnish 34R or 6A for gravel filter berm.
916.05 Inlet Protection Geotextile and Stone and Drop Inlet Sediment Trap
Furnish geotextile blanket meeting the requirements of subsection 910.03.A . Furnish 34R, 46G, or 6A.
916.06 Sand Fence and Dune Stabilization
Furnish HDPE mesh fabric with a design opening of ½ to 1 inch. Minimum sand fence height is 4 feet.
916.07 Turbidity Curtain
Deliver t urbidity curtain pre- assembled that includes the geosynthetic fabric, connection and securing mechanisms, flotation devices, stakes, and ballast chain.
A.Geosynthetic. Provide g eosynthetic for turbidity curtain meet ing the minimum physical requirements for stabilization geotextile that except permittivity must be no greater than 0.2 second -¹ as specified by ASTM D4491/D4491M , and the trapezoidal tear strength must be least 50 pounds in accordance with ASTM D4533/D4533M . The Contractor may use polymer -impregnated geosynthetics instead of meeting permittivity and opening size requirements. Hemmed pockets to accommodate flotation devices and bottom weights must be sewn or heat bonded . Panel ends must include metal grommets through a reinforced hem . Tie connections between panels with synthetic or wire rope to prevent water flow through the joint.
B.Flotation . Furnish closed cell polystyrene f lotation devices . Determine the required buoyancy based on site conditions . Flotation devices must ensure adequate freeboard to prevent overtopping.
C.Stakes. If using stakes to maintain curtain alignment, provide hardwood or steel stakes of lengths and cross sections capable of supporting the curtain. The Contractor may use external supports with embedment depths greater than 1½ feet . Maximum stake spacing is 6½ feet. MDOT Standard Specifications for Construction Section 916 9-131 D. Hardware. Hardware, including stakes, ballast chain, connection bolts, reinforcement plates, and tension cables , must be galvanized, stainless steel, or aluminum and corrosion resistant . The mass of the ballast chain must be at least 0.7 pound per foot and be capable of maintaining the geosynthetic in a vertical position.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 938–941 of 1,146.